UNIT OVERVIEW

Have you ever wondered why the Moon doesn't fly off into space? Why do apples fall downward? Why do astronauts float inside the International Space Station even though they're still close to Earth?

The answer lies in a law discovered by Sir Isaac Newton over 300 years ago. Newton realised that the same force pulling an apple to the ground also keeps the Moon orbiting Earth and planets orbiting the Sun. This was revolutionary—celestial bodies follow the same physical laws as objects on Earth.

In this unit, you will learn:

• How Newton's Law of Universal Gravitation describes the attractive force between any two masses
• Why gravitational force depends on both mass and distance
• How to calculate gravitational forces between everyday objects, planets, and stars
• The relationship between gravitational field strength (g) and the universal gravitational constant (G)
• How weight changes depending on where you are in the universe
• The connection between gravitational force and orbital motion
• How to verify Newton's second law experimentally using a trolley and ticker timer

Real-Life Applications: